Ageing and the immune system

Question 1

what age does immune decline usually occur?

Answer 1

~60-70 yrs

Question 2

what type of immune response decreases with age?

Answer 2

especially in T cell and B cell response

Decrease in response to vaccine

Question 3

what antibody is present in breast milk?

Answer 3

IgA

Question 4

what is senescence?

Answer 4

Biological aging
- is the gradual deterioration of functional characteristics

Question 5

what is immunosenescence?

Answer 5

Gradual deterioration of immune system function
- reduced ability to fight infection
- reduced vaccine efficacy
- reduced tumour clearance

Question 6

why does age effect immune response?

Answer 6

The aged immune system is less efficient at recognising and limiting infections
- increased incidence of infectious disease
- increased severity of infectious disease

Mechanical barriers weaken- less protective

Question 7

what is IPD?

Answer 7

invasive pneumococcal disease

Question 8

what is CAP?

Answer 8

community acquired pneumonia

Question 9

where are the covid deaths increasing?

Answer 9

with age
deaths concentrated in older individuals

Question 10

who is at greater risk of influenza?

Answer 10

Older adults at greater risk for severe influenza infection or complications of influenza

Question 11

what are the features of Shinges (Herpes zoster) infection?

Answer 11

• reactivation of varicella zoster virus
• presenst as rash with acute pain, the rash follows the nerve path
• Complications include postherpetic neuralgia, vision loss, hearing loss, pneumonia, secondary bacterial infection

Question 12

what is the efficacy of the shingles vaccine with age?

Answer 12

50-59 yrs= 70%
60-69 yrs= 64%
70-79 yrs= 41%
80+ yrs = 18% (no longer funded)

Question 13

what is oligoclonal?

Answer 13

Derived from a few clones

Question 14

what is monoclonal?

Answer 14

derived from one clone

Question 15

what is polyclonal?

Answer 15

derived from many clones

Question 16

what is the normal immune response?

Answer 16

polyclonal

Question 17

what drives immunosenescence?

Answer 17

Reduced diversity of adaptive immune cells
- reduced T cell diversity
- reduced B cell diversity
- Due to reduced proportion of naive cells
- Oligo-clonal expansion of memory cells

Question 18

why does the proportion of naive cells decrease with age?

Answer 18

the amount of precursor memory cells increases

Question 19

why does T cell function decrease with age?

Answer 19

Decreased number of naive T cells in older age
- Progressive decrease in thymic output (thymic involution)
- Number of T cells remains constant (existing naive cell longlived)

Question 20

how does the thymus change with age?

Answer 20

Increases in fat content
decreases in size- fewer T cells coming from the thymus

Question 21

what us memory inflation in the immune system?

Answer 21

Accumulation of CD8 T cells with limited TCR repertoire (memory T cells)

Question 22

why does T cell function decrease with an accumulation of memory T cells?

Answer 22

Increased proportion of memory T cells
- Accumulation of “virtual memory” CD8 T cells- cells that have a memory phenotype but are antigen-naive and conventional memory T cells
- Reduced functionality of virtual memory and conventional memory T cell subsets

Question 23

what causes reduced function of mature B cells with age?

Answer 23

Inefficient generation of memory B cells

Question 24

what causes impaired B cell development in age?

Answer 24

• decreased numbers of early B cell progenitors
• decreased expression of gene s important for B cell development

Question 25

what causes decreased B cell function in the aged?

Answer 25

-Reduced function of mature B cells
-Impaired B cell development
-Alteration in the size and composition of the B cell repertorie (the number of different BCR expressed by an individual)

Question 26

what are the outcomes of decreased B cells function?

Answer 26

Heightened susceptibility to infection, decreased antibody responses to vaccination, increase in the incidence of autoimmune disorders

Question 27

what is the SLC in B cells?

Answer 27

surrogate light chain, important for B cell development to signal productive rearrangement of the heavy chain

Question 28

what are ABCs?

Answer 28

Age-associated B cells

Question 29

what are the features of Age Associated B cells?

Answer 29

• they rely on TLR7 or TLR9 signals for formation and activation- they don’t respond to BCR signaling alone.
• increased in autoimmune/autoinflammatory disease
• enriched for autoantibody specificities

Question 30

what is the mechanism for inflammaging?

Answer 30

Heterogeneous exogenous and endogenous danger stimuli interact with a limited repetoir of sensors expressed on the cell surface and in the cytoplasm.
These result in a limited number of inflammatory responses.
With age, the pro-inflammatory output increase and becomes detrimental.